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Sept. 10, 1957 J. c. wHnEsl-:LL 2,805,455

MOLDED DIAPHRAGM MAT Filed Sept. 15, 1955 2 Sheets-Sheet 1 Jg J5 ,7T/.41 26 ,J5 Jg; z

Z5 Zzyezgfar Sept. 10, 1957 J. c. wHrrEsELl..N l 2,805,455

MOLDED DIAPHRAGM MAT Filed Sept. l5., 1955 2 Sheets-Sheet 2 www1..

Rami! MGLDED IAPRGM MAT John C. Whiteseil, Chicago, ill., signor to Crane Co., Chicago, lll., a corporation of iliinois Application September i5, 1%5, Serial No. 534,449 12 Claims. (Cl. 2.2-42) This invention relates broadly to a pressure-applying diaphragm for mold-forming apparatus, and more particularly to such a diaphragm which does not stretch in any direction when expanded in application of pressure.

One type of apparatus for making molds comprises a pressure head or cap across which an elastic expansible diaphragm is secured to dene a fluid-tight pressure chamber, the diaphragm being arranged to press against sand or other mold material in a molding flask or the like to compact the material about a pattern upon admission of a duid under pressure such as compressed air into the chamber. Such apparatus has certain advantages over other types of mold-forming apparatus, but heretofore the diaphragms employed have had relatively short useful life, failing largely because of repeated stretching thereof in the application of pressure to molds. The present invention provides a diaphragm for such use which has a greatly prolonged life as compared to prior diaphragms and accordingly permits continuous use of the apparatus for longer periods without interruption for diaphragm repair or replacement. The invention thus results in great economies in reducing interruptions to production and time and labor involved in replacing impaired diaphragms, as well as the number of diaphragms required. The advantageous results are accomplished by providing a diaphragm so corrugated, as more fully disclosed hereinafter, as to expand upon application of pressure without stretching in any direction, the main cause for early failure of the diaphragm being thus eliminated.

It is an object of the invention to provide a pressureapplying diaphragm mat for mold-forming apparatus so formed as'to avoid stretching in any direction when expanded in operation to apply pressure.

It is also an object to provide a pressure-applying diaphragm for mold-forming apparatus so corrugated as to avoid stretching in any direction upon expansion in applying pressure.

Another object of the invention is the provision of a pressure-applying diaphragm for mold-forming apparatus, having corrugations therein of Such location and shape as to prevent stretching of the diaphragm in any direction upon expansion in response to the application of tluid pressure.

Another obiect is the provision of a pressure-applying diaphragm for mold-forming apparatus, molded or similarly formed with corrugations therein extending in encircling relation to the center of the diaphragm to avoid stretching in any radial direction upon kexpansion in applying pressure.

A further object is the provision ci mold-forming apparatus employing a pressure-applying diaphragm corrugated to provide for expansion thereof without stretching in any direction.

Another object is the provision in mold-forming apparatus of a pressure-applying diaphragm so corrugated as to avoid stretching in any direction while expanding in the application of pressure.

Other and further Objects, advantages and features of Patented Sept. 10, 1957 the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a vertical sectional view through a mold forming apparatus employing one embodiment of the diaphragm of this invention;

Fig. 2 is an enlarged plan view of the diaphragm shown in Fig. l;

Fig. 3 is a transverse sectional view through the diaphragm taken as indicated by the line 3-3 of Fig. 2;

Fig. 4 is a longitudinal sectional view through the diaphragm taken as indicated by the line 4-4 of Fig. 2;

Fig. 5 is a further sectional view taken as indicated by the line 5-5 of Fig. 2; and

Fig. 6 is a sectional View similar to Fig. 4, but illustrating another embodiment.

Referring rst to Fig, l of the drawings, there is shown an apparatus for making molds comprising a flanged mold box 10, which may be a part of a molding ilask, such as the cope or drag, containing sand 11 or other mold material and disposed on a pattern plate 12 on which is mounted a pattern 13 about which the sand is to be compacted. A pressure head 14 generally conforming in shape to the periphery of the mold box, in this case of the usual rectangular form, has a ange about its lower edge to which is peripherally secured an expansible diaphragm 15. The diaphragm in normal position lies substantially atly across the head, and deiines therewith a fluid-tight pressure chamber 16. In the present instances, the diaphragm is secured to the ange of the head 14 by insertion between the iiange of the head and a clamping ring 17 which engages on the upper ange of the mold box, the entire assembly of mold box, ring, diaphragm and head being tightly secured together by means of C-clamps 18 engaging the flange of the head and the corresponding flange on the mold box, although other appropriate means may be employed. Any suitable fluid under pressure may be admitted to the pressure chamber through a conduit 19 under control of the valve 2Q, with the pressure indicated by means of the gage 2l, the diaphragm then applying pressure to the sand to form the mold. Suction means might be employed for retracting the diaphragm 15, but are unnecessary because the diaphragin is self-retracting.

Referring now more particularly to Figs. 2 to 4 inclusive, the diaphragm 15 is formed from a flexible sheet of rubber or similar material which may be molded, set, or otherwise formed into corrugations or the like, while retaining substantially the same ilexibility in portions so formed as in unformed portions. in the present instance, the diaphragm is formed of rubber, but as indicated, other materials having the moldable or formable quality of rubber may be employed, For convenience7 such materials are herein designated as rubber-like. The diaphragm is formed with a substantially flat central portion 22 which largely provides the main pressure area and a substantially at peripheral portion 23, on one face of which is formed a bead 24 to seat in a corresponding groove in the ring 17 for tight sealing engagement. A similar bead may of course be formed on the other face of the peripheral portion to engage in a groove formed in the iiange of the head i4. About the flat central portion 22 extends a plurality of generally annular or endless corrugations 25 molded in the sheet and retaining substantially the same flexibility and otherv characteristics as the central and peripheral portions but holding their corrugated form under normal conditions. It is preferable that, as shown, the annular shape of the corrugations in plan conform generally to the shape of the diaphragm, with relatively straight portions extending parallel to the edges of the diaphragm. Sharp corners on these annularly extending corrugations are to be avoided, however, and accordingly each corner is formed abouta suitable radius, the centers for the corresponding corners of all the corrugations being the same. The corrugations are therefore substantially parallel to each other throughout, lying one within another, andencircling the central'portion 22. lt will be Vseen that thus the corrugations extend between the fiat central and peripheral portions across all radii from the center of the sheet, so that no at'or unoorrugated portions extend radially from the central-to the peripheral portion. When pressure is applied to the diaphragm so as vto compress the sand il into the desired compactness about the pattern to form the mold, the corrugations yield or are flattened so that the Vdiaphragm-mayf expand without stretching in any direction and conform generally to the pattern contour, and upon release of the pressure the corrugations return rto their set orfmolded form to bring the diaphragm back to its normal condition. Since the Vdiaphragm lo', is substantially rectangular, and the corrugations are of a shape avoiding sharp corners, flat areas would be left adjacent the corners of the diaphragm which might under certain conditions be subjected to stretching. To avoid this possibility, the sheet is molded at the corner areas with bulged portions Zo, which may be generally oval in plan, as shown, or of other suitable shape. These bulged portions, which may extend from either face of the diaphragm, cooperate with the corrugations 25 to counteract any stretching of the diaphragm, flattening upon any tendency of the diaphragm to stretch and resuming their normal bulged configuration when pressure is released.

In Fig. 6, there is shown a transverse section through a diaphragm 27 which is substantially similar to the diaphragm l5, having the flat peripheral portion 23 and the bead 24, but eliminating the dat central portion 22. The corrugations 28 are substantially similar to the corrugations 25 of the diaphragm 15 and are molded in the sheet extending from immediately adjacent the center to the peripheral portion, soV that substantially all of the sheet inwardly of the portion 23 is formed with these annular corrugations. The bulged portions 25 are preferably also provided in the diaphragm 27. It will be apparent that the corrugations 28 extend across all radii from the center of the diaphragm, and act in the same manner as the corrugations 25 to prevent stretching of the diaphragm. The corrugated formation of diaphragm 27 provides for greater expansion than in the diaphragm l5.

It will be appreciated that corrugations not of annular or endless shape in plan may be employed instead of the corrugations 25 or 28, arranged about the center or the central portion in such staggered or lapped relation to each other as to extend across all radii or radial lines from the center or central portion. Substantially the same result of avoiding any radially extending at portion directly connecting the periphery with the center or central portion, thus preventing stretching in any direction, is obtained as with the annular corrugations.

It will accordingly be understood that the two embodiments shown and described are forV purposes of illustration only and the invention may take any of a plurality of forms without departing from the scope of the invention as hereinafter defined.

I claim:

l. Apparatus for making molds comprising a pressure head and a pressure-applying diaphragm defining therewith a duid-tight pressure chamber and expansible without stretching in any direction, said diaphragm comprising a sheet of rubber-like material having formed about the center thereof at least one corrugation of generally annular shape devoid of sharp corners in plan attening upon expansion of the diaphragm.

2. Apparatus for making molds comprising a pressure head and a pressure-applying diaphragm defining therewith a fluid-tight pressure chamber and expansible without stretching in any direction, said diaphragmV comprising a Li sheet of Yrubber-like material having formed about the center thereof a plurality of corrugations each of generally annular shape devoid of sharp corners in plan located one within another flattening upon expansion of the diaphragm.

3. Apparatus for forming molds comprising a pressure head and a pressure-applying diaphragm expansible without stretching in any 'direction defining therewith a iuidtight chamber, said diaphragm comprising a sheet of rubber-like material having formed about the center thereof a plurality of corrugations extending across all radii from said center and attening upon Y expansion of the diaphragm.

4. Apparatus for forming molds comprising a pressure head and a pressure-applying diaphragm defining with the head a duid-tight pressure chamber and expansible without stretching in any direction, said diaphragm comprising a sheet of rubber-like material having a corrugated formation between the center and periphery theerof leaving no iiatportion extending radially between the center and periphery. Y

5. A pressure-applying diaphragm for pressure molding apparatus, comprising a sheet of Vrubber-like material having about the center thereof at least one corrugation of generally annular shape devoid of sharp corners in plan flattening upon expansion of the diaphragm to avoid stretching thereof in any direction.

6. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having a corrugated formation between the center and periphery thereof leaving no flat portion extending radially between the center and periphery, said formation flattening to counteract stretching of the diaphragm in any direction.

7. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having a substantially flat central portion and at least one corrugation formed therein of generally annular form devoid of sharp corners in plan encircling said central portion and flattening upon expansion of the diaphragmV to prevent stretching thereof in any direction.

8. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having formed about the center thereof a plurality of corrugations extending across all radii from said center and flattening upon expansion of the diaphragm to avoid stretching thereof.

9. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having a substantially ilat central portion and having formed therein about said central portion a plurality of corrugations extending across all radial lines from said portion and flattening upon expansion of the diaphragm to counteract stretching thereof.

10. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having formed about the center thereof a series of corrugations each of endless formation devoid of sharp corners in plan located one within another flattening upon expansion of the diaphragm to avoid stretching thereof in any direction, said series of corrugations extending outwardly from immediately adjacent said center.

1l. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material having formed about the center thereof a plurality of corrugations extending across all radii from said center leaving no dat portion extending radially from the center to the portion of the sheet outwardly of said corrugations, said plurality of corrugations extending outwardly from immediately adjacent the center and attening upon expansion of the diaphragm to prevent stretching thereof in any direction.

l2. A pressure-applying diaphragm for mold-forming apparatus, comprising a sheet of rubber-like material hav- 5 ing a corrugated formation between the center and periphery thereof leaving in the sheet no flat portion extending radially between the center and periphery and also having formed in otherwise at portions thereof between said formation and periphery a plurality of bulged portions, sad formation and bulged portions flattening upon expansion of the diaphragm to prevent `stretching thereof in any direction.

Referencesv Cited in the tile of this patent UNITED STATES PATENTS 2,593,292 Gaugler Apr. 15, 1952 2,698,976 Taccone Ian. 11, 1955 FOREIGN PATENTS 649,837 Germany Sept. 6, 1937 

